This invention relates to apparatus for applying a sealant composition to a road surface. It is now universally recognized that the service lives of highway pavements are greatly dependent on the ability to prevent water penetration through joints or cracks in the highway surface. This is especially critical for old roads needing maintenance. A technique gaining acceptance in this field is the application of an integral filler or membrane over the affected area. Not only is this approach cost and performance effective, but it serves to retard reflective cracking should the road be overlayed with bituminous concrete at a later date. Indeed, in some states, e.g., Pennsylvania, the hot extrusion of a fiberized membrane over the joints or cracks prior to rehabilitation paving is a standard specification. Critical parameters for such membranes are their width and thickness. Current applicators used for this purpose can not accurately control either the thickness or width of the applied composition. Moreover, ability to apply the membrane in a reasonably straight line is difficult.